This apparatus can effect pyrolysis of hydrocarbon containing material at high temperature of 400 to 500.degree. C and under vacuum in consecutive batches. The apparatus comprises a cylindrical drum rotatable at a variable speed about a horizontal axis and spacedly surrounded by a heat insulating sheath; a gas burner heats the rotating drum along its entire length from the exterior of the same; a chimney communicates with the space between the drum and the sheath, which has ventilation openings closable by trap doors; the drum is supported by bearings so to allow its axial thermal expansion. A manifold system of filters is stationarily mounted within the rotating drum to filter out fine solid residues from the pyrolytic gases and vapors. This manifold is connected to a discharge tube which exits from one end of the drum and is fitted with a sealing joint to seal the drum around the stationary discharge tube. This joint has a passage for admitting into the drum emergency inert gas to prevent atmospheric air into the drum in the event of an accidental leak of the rotary joint. The drum has an access door and a system to swing the door open and to properly seal the door in position on the drum.
